I will go to the bank by the wood and become undisguised and naked, I am mad for it to be in contact with me.

Meaning

Walt is saying that he wants to return to nature in a spiritual sense through a physical means. To Walt, clothes are a disguise of who people really are in their natural, unadorned state. He’s going down to the river and getting naked so he can go for a swim, because he longs to be completely submerged in nature.